With a baton the general directs soldiers and the conductor musicians, and in the nanoworld the rodlike shape also means control, as this form enhances magnetic and coercive properties of crystalline aggregates. Also reported here is a tunable synthetic method, in which the overall shape of the crystal is determined by a balance of kinetically and thermodynamically controlled growth mechanisms. The graphic shows one example of the degree of ordering available in the crystalline through this method.
The extensive design effort for KSTAR has been focused on two major aspects of the KSTAR project mission - steady-state-operation capability and advanced tokamak physics. The steady state aspect of the mission is reflected in the choice of superconducting magnets, provision of actively cooled in-vessel components, and long pulse current drive and heating systems. The advanced tokamak aspect of the mission is incorporated in the design features associated with flexible plasma shaping, double null divertor and passive stabilizers, internal control coils and a comprehensive set of diagnostics. Substantial progress in engineering has been made on superconducting magnets, the vacuum vessel, plasma facing components and power supplies. The new KSTAR experimental facility with cryogenic system and deionized water cooling and main power systems has been designed, and the construction work is under way for completion in 2004.
The Korea Superconducting Tokamak Advanced Research (KSTAR) project is the major effort of the national fusion programme of the Republic of Korea. Its aim is to develop a steady state capable advanced superconducting tokamak to establish a scientific and technological basis for an attractive fusion reactor. The major parameters of the tokamak are: major radius 1.8 m, minor radius 0.5 m, toroidal field 3.5 T and plasma current 2 MA, with a strongly shaped plasma cross-section and double null divertor. The initial pulse length provided by the poloidal magnet system is 20 s, but the pulse length can be increased to 300 s through non-inductive current drive. The plasma heating and current drive system consists of neutral beams, ion cyclotron waves, lower hybrid waves and electron cyclotron waves for flexible profile control in advanced tokamak operating modes. A comprehensive set of diagnostics is planned for plasma control, performance evaluation and physics understanding. The project has completed its conceptual design and moved to the engineering design and construction phase. The target date for the first plasma is 2002.
We report a fabrication of arrays of ferromagnetic iron and cobalt nanocluster wires (NCWs), ranging from 8 to 10 nm in diameter and up to a few millimeters in length. The iron and the cobalt nanoclusters served as building blocks of the corresponding ferromagnetic NCWs. The iron and the cobalt nanoclusters were produced by thermally decomposing the corresponding metal carbonyl vapors with a resistive heater placed in the middle of a pair of permanent disk magnets. The NCWs were produced through pile-up of metallic nanoclusters along lines of magnetic flux, perpendicularly to the substrates attached to a pair of permanent disk magnet surfaces. We observed coercivities as large as 248 and 964 oersteds and remanences as high as 61 and 71% for the ferromagnetic iron and cobalt NCWs, respectively.There is no doubt that the nanowires (NWs) have drawn a special attention from all of us because of their properties quite different from the bulk, resulting from nanometer-scale onedimensional structure and their potential applicability to engineer a variety of state-of-the-art nanodevices. 1 For instance, the most spectacular of these may be arrays of ferromagnetic NWs which may be useful for a perpendicular magnetic recording. [2][3][4] In this work, we report a very easy fabrication of arrays of ferromagnetic nanocluster wires (NCWs), including characterization of their structures, physical dimensions, and magnetic properties. Here, the NCW is named because the NW consists of metallic nanoclusters.The experimental setup used in the present experiment is quite simple, as represented in Figure 1. Here, the stainless steel reaction chamber is very similar to the one used to generate a variety of metallic nanoclusters by thermally decomposing metal carbonyl vapors with a resistive heater in the previous work. 5 The reaction chamber was evacuated with a 50 L/s mechanical pump down to 10 -3 Torr. Even at this vacuum level, metallic
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